I just got the Martin Best Ensemble's 1980s CD of the Cantigas de Santa Maria (Nimbus NI 5081), and this item surprised me:

Cantiga 159: The Lost Steak

The surprise was that I already knew the tune, or something very close to it. I'd learned it from the fiddler in a band I was in more than 20 years ago:

X:1
T:Galician Solstice Song
H:Learnt by Panda Smith at a Rainbow Gathering in northern Portugal
M:4/4
L:1/4
Q:1/2=100
K:EMin
aa/g/ f/e/d|gg fz|a/b/a/g/ f/e/d|gg fz:|
ee/e/ ff/f/|dc cz|ee/e/    ff/f/|de ez:|

So. We have a mediaeval Christian song about an unusually daft miracle reinterpreted by a bunch of knit-your-own-windmill hippies as a pagan ritual tune. But, in exactly the same region as where the miracle song originated. How did this happen?